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Spiral steel pipe is a kind of spiral seam steel pipe which is made of strip steel coil as raw material, often formed by warm extrusion and welded by automatic double-wire double-side submerged arc welding process.
(1) raw materials that is, strip coil, welding wire, flux.They are subjected to strict physical and chemical tests before they are put into use.
(2) The butt joint of strip steel head and tail adopts single-wire or double-wire submerged arc welding, and automatic submerged arc welding is adopted after rolling into steel pipe.
(3) before forming, strip steel after leveling, edge cutting, edge planing, surface cleaning and conveying and edge bending treatment.
(4) The electric contact pressure gauge is used to control the pressure of the oil cylinder pressed on both sides of the conveyor to ensure the smooth transport of strip steel.
(5) the use of external control or internal control roller forming.
(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of wrong side and the weld gap are strictly controlled.
(7) Single wire or double wire submerged arc welding is adopted for both internal and external welding by Lincoln welding machine in the United States, so as to obtain stable welding specifications.
(8) The welds after welding are inspected by online continuous ultrasonic automatic flaw tester to ensure 100% nondestructive testing coverage of spiral welds.If there is any defect, it will automatically alarm and spray mark, so that the production workers can adjust the process parameters at any time and eliminate the defect in time.
(9) The steel pipe is cut into single pieces by air plasma cutting machine.
(10) After being cut into a single steel pipe, each batch of steel pipes shall undergo strict first inspection system to check the mechanical properties, chemical composition, dissolution status of the weld, the surface quality of the steel pipe and pass nondestructive inspection to ensure that the pipe making process is qualified before being formally put into production.
(11) The parts on the weld with continuous acoustic flaw detection marks shall be rechecked by manual ultrasonic and X-ray. If there are any defects, they shall be repaired and then undergo nondestructive inspection again until the defects are confirmed to be eliminated.
(12) All the tubes where the butt-welding welds of strip steel and the T-joint intersecting the spiral welds are inspected by X-ray TV or film.
(13) Each steel pipe is subjected to hydrostatic pressure test, and the pressure is radial sealed.The test pressure and time are strictly controlled by the tube hydraulic microcomputer testing device.The test parameters are automatically printed and recorded.
(14) The pipe end is machined so that the verticality of the end face, groove Angle and blunt edge can be accurately controlled.